The paper deals with the analysis of the behaviour of complex structures made of ancient wood. With reference to a study case, which is the roofing structures of the Diplomatic Hall of the Royal Palace of Naples, the detailed geometrical and mechanical surveys are shown. On the basis of the results of the structural analysis, by means of a 3D model, the safety checks, accordingtothe EC5 provisions, have identified the capacity of the structure in terms of strength and deformation and then the necessity of a structural retrofitting. Details of the proposed restoration intervention, based on the mixed technologies, are presented. © 2005 Taylor & Francis Group.